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Related Experiment Videos

Steady state voltages in the frog lens.

R T Mathias, J L Rae

    Current Eye Research
    |April 1, 1985
    PubMed
    Summary
    This summary is machine-generated.

    This study quantifies active sodium-potassium (Na/K) pump current density in lens surface cells and characterizes ion channel selectivity in fiber cells. Findings support a model predicting circulating currents and voltage gradients essential for ocular electro-chemical steady state.

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    Area of Science:

    • Ophthalmology
    • Cell Physiology
    • Biophysics

    Background:

    • The ocular lens maintains electrochemical steady state via cellular transport.
    • Active Na/K transport and passive ion leaks are critical for lens function.
    • Previous work localized Na/K transport to anterior lens surface cells.

    Purpose of the Study:

    • To estimate Na/K pump current density in lens surface cells.
    • To determine ion channel selectivity in lens fiber cell membranes.
    • To model electrochemical steady state and predict voltage gradients.

    Main Methods:

    • Measured intracellular voltage changes upon exposure to ouabain to estimate pump current density.
    • Utilized impedance data to infer passive ion permeability.

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  • Developed a model relating transport properties to resting voltages.

    • Main Results:

    • Estimated Na/K pump current density at 2-4 μA/cm².
    • Suggested K+ passive leak is primarily across surface cell membranes.
    • Identified Na+ and Cl- selective channels in fiber cells, with fewer K+ channels.
    • Model predictions of circulating currents and voltage gradients agreed with measurements.

    Conclusions:

    • Localized transport properties predict lens electrochemical steady state.
    • The findings provide a quantitative basis for understanding lens electrophysiology.
    • Further research is needed to pinpoint the exact location of K+ leak channels.